F# PJ12

    open System.Numerics

    let seqTriNum = Seq.initInfinite (fun index ->
        let bigIndex = BigInteger(index)
        (bigIndex + 1I) * bigIndex / 2I)

    let divCount (number : BigInteger) =
        let rec loop (count : BigInteger) (i : BigInteger) =
            match number with
            | _ when (number = 0I || number = 1I || number = 2I) -> number
            | _ when i = 0I -> count + 1I  //Counting the element as appears to be its divisor
            | _ when number % i = 0I -> loop (count + 1I) (i - 1I)
            | _ -> loop count (i - 1I)
        loop 0I (number/2I + 1I)

    let result = Seq.find (fun x -> divCount x > 500I) seqTriNum